RU2580667C1 - Method for laser wireless retro-reflector distributed optical switching and system therefor - Google Patents

Abstract

FIELD: communication.

SUBSTANCE: invention relates to optical communication and can be used in means of switching digital devices, in which optical wireless switching of devices is performed. System comprises in each participating in switching facility demultiplexers with a group of lasers, selected and included object, and is involved in switching facilities comprises retroreflective units, wherein each laser demultiplexer constantly matches only one retroreflector modules receiving transmitted in free space signals that laser and return them in direction of signal source, and entering module signals lasers vary in frequency, each retroreflective unit corresponds to one or more involved in switching objects and contains binary memory elements controlled by object and prohibit or allow retroreflective module returns received from demultiplexer corresponding memory element of signal, if memory element is mounted, respectively, in prohibiting or permitting return of state signal. Participating in switching object - source for selecting receive signals of objects - receiver chooses demultiplexer and includes lasers for sending signals at same time group set out in respective receiver retroreflective units and through receivers, modulating signal source is routed to module signal receiver, receiver makes to memory of corresponding retroreflective unit information on state of receiver, and source checks status of memory to select actions with receiver.

EFFECT: technical result consists in providing switching devices with selection of direction of transmitting signals by switching source of separate lasers selected from a group of lasers.

2 cl, 10 dwg

Description

The invention relates to the field of computer technology and can be used as a means of switching digital devices.

The switching system is the central link of the modern control and computing system, which forms the system as a whole from a set of active data processing devices that are not interconnected (hereinafter objects, if detailing is not required). At the same time, it requires the absence of internal switching conflicts, high switching speed, fault tolerance.

It is often impossible to plan the circulation of message sources to the message receiver and to avoid conflicts at the input of the message receiver (conflicts external to the switching system). It is required to quickly eliminate external conflicts by means of a switching system.

It is often also required to simultaneously send a message from one source to a group of receivers and to be able to quickly change the composition of a group of such receivers.

To speed up the execution of applications for connecting sources and receivers of information received in the switching system, it is necessary to quickly determine the status of receivers (in particular, the ability of receivers to receive a currently transmitted message). Acceleration is achieved if information about the status of the receivers is stored in the switching system and it is not necessary to obtain them by contacting the receivers directly.

These requirements are difficult to provide by electronic means. The task is simplified when using the optoelectronics means proposed in the patent.

To meet the above requirements, the patent proposes a system and method for laser wireless retroreflective distributed optical switching.

As a prototype, the well-known method of increasing the fault tolerance of distributed optical switching and the conflict-free wireless retroreflective switch that implements it are described in patent No. 2538314 and the article (Organization of switched direct connections of active objects of complex digital systems // Control of large systems. - M. IPU RAS, 2014). issue 49.P. 148-165, _results_new.php? publication_id = 19284).

In the prototype, a source for sending a digital message to a given receiver directs it to an intermediate retroreflector module (RCM) and then to the receiver using a laser beam oriented in space using an optical demultiplexer. In this design, each message source / receiver contains two demultiplexers and the set of demultiplexers of all sources acts as a distributed switch connecting message sources and receivers through RCM modules corresponding to the receivers. The prototype offers two types of optical demultiplexers - the first of them selects the direction of the optical beam by changing the orientation of the micromirrors, the second uses switches on the vanadium compounds for the same purpose, which switch from the state of light transmission to the reflecting state.

Disadvantages of the subtype. The first type of prototype demultiplexer currently requires switching at least three microseconds, which is slow for many applications. The second demultiplexer can switch in the femtosecond range, but it is characterized by interference: when light passes through the elements of the demultiplexer, part of it passes through other elements and creates interference at the output. To combat interference, it is necessary to introduce interference attenuators, which also attenuate, but to a lesser extent, the useful signal, which leads to energy losses.

In the prototype, the message source cannot send a message simultaneously to a group of receivers, and thus the above requirement for simultaneous multicast transmission of a message is not satisfied. The prototype also does not store distributed information, outside the receivers, about their status. To determine this state, a fairly slow call to the receiver is required.

The objective of the present invention is to eliminate these disadvantages of the prototype.

The technical result for the switching system is that it includes distributed technical means for switching signals directly by lasers, for simultaneously transmitting a source message to a group of receivers, technical means for fixing the status of receivers located outside the receivers.

The technical result for the system is achieved by the fact that the system contains demultiplexers in each object participating in the switching with a group of lasers selected and turned on by this object, and contains retroreflector modules outside of the objects participating in the switching, and each laser of the demultiplexer always corresponds to only one of the retroreflector modules receiving the signals of this laser transmitted in free space and those returning them in the direction of the signal source, the signals of the lasers p they are differentiated by frequency, and each retroreflector module corresponds to one or several objects participating in the switching and contains binary memory elements controlled by this object and prohibiting or allowing the retroreflector module to return the signal received from the demultiplexer if the memory element is set respectively to prohibit or enable return signal condition.

The technical result for the method consists in performing high-speed switching of transmitted messages, including messages simultaneously transmitted by one source to a group of receivers, switching excluding mutual interference from simultaneously transmitted by different sources of message signals, as well as in distributed storage of information about the status of receivers outside the receivers.

The technical result for the switching method is achieved in that the object participating in the switching, the source for the selection of receiving objects, receivers, is selected in the demultiplexer and includes lasers for sending signals simultaneously to the group of retroreflector modules assigned to the receivers and through them receivers, modulating the receiver signals with the source signals, sent to the module by the receiver and returned to it by the module, the receiver introducing into the memory of the corresponding retroreflector module information about the state of the receiver, and the source determines the state of this memory for choosing its actions with the receiver.

The technical nature and principle of operation of the proposed system are illustrated by drawings.

FIG. 1. Demultiplexer for simultaneous communication with a group of receivers

FIG. 2. Laser unit with control device

FIG. 3. Retroreflector module

FIG. 4. Fixed mirror system

FIG. 5. Location of signal receivers

FIG. 6. Partially transparent mirror

FIG. 7. Switch components of each dial-up object

FIG. 8. An example of a dial-up system

FIG. 9. Demultiplexer for communication with one receiver

FIG. 10. Laser unit with a control device for communication with one receiver

The devices shown in the drawings should be considered as examples of the technical feasibility of the system and method proposed in the patent.

A brief description of the proposed switching system. The switched objects contain built-in means of distributed optical switching and retroreflector modules (RCM) are located outside these objects. The first tools contain sources and receivers of optical signals, as well as demultiplexers of these signals, including sets of lasers in an amount sufficient to perform switching of objects. The lasers in the set are arranged arbitrarily, for example, in the form of a line or a grating on a plane (hereinafter, sets of lasers are considered as laser gratings). The demultiplexer selects lasers in the laser array that can direct their signals to the required retroreflector modules. Each retroreflector module corresponds to a laser or several lasers in the laser array. Retroreflector modules contain memory elements, information in which the lasers of demultiplexers are recorded, and this information changes the ability of the retroreflector module to return signals to their source, which affects the interaction of the module with switched objects.

A brief description of the proposed switching method. Retroreflector modules act as intermediaries between sources and receivers of optical signals (including message signals). In this case, the source sends signals not directly to the receiver, but to the retroreflector module allocated for communication with the receiver, changing its state. To receive a source message, the receiver sends signals to the retroreflector module that interrogate the state of the module, and as a result receives the value of the source signals arriving at this module. Using a demultiplexer, the source object can send a message simultaneously to a group of receivers. Also, a group of receivers can receive a message from a single source, while simultaneously addressing the retroreflector module to which the source sends a message. In particular, an object can change the state of the internal memory of the retroreflector module allocated to it in order to most quickly inform other objects about its possibilities for interacting with them.

The signals from the demultiplexer lasers arriving in the retroreflector module return to the photodetectors the objects that sent the signals.

Detailed description of the proposed switching system. The system consists of demultiplexers located in each source and receiver of messages, and a group of intermediate retroreflector modules located outside of switched objects so that the optical signals sent by objects enter the module selected by the object.

Consider the design of a distributed switch that extends the capabilities of the prototype switch. We begin our discussion with the demultiplexer shown in FIG. one.

Here 1 is a set of external signals sent by an object for controlling lattice lasers, 2 is an input of message signals and service signals, block 3 is a group of lasers with a control device, 4 is a block for generating a power signal for lattice lasers, 5 is a register, 6 is a controller.

The nodes of the demultiplexer interact as follows. From the power supply generating unit for the lasers 4, when the signals of group 2 controlling the unit 4 are supplied, the power signal is supplied to all units 3. As shown in FIG. 2, these signals, if there is a signal, the logical unit in the discharge of a set of external signals coming from the object will turn on the grating lasers corresponding to the discharge.

Thus, lasers are turned on, which must simultaneously give out optical signals. These signals must be sent to the RCM corresponding to the selected lasers.

The demultiplexer can be used in two configurations: it can be a single unit with the design of the switched object or run as a separate device. In the first case, nodes 5 and 6 in FIG. 1, since even with a large number of connections 1, these connections are inside the integrated circuit. In the second case, a large number of inputs into the demultiplexer causes difficulties. It is proposed in this case to add a shift register 5, in which the loading of signals 1 is performed sequentially. Additionally, you can enter a programmable controller 6, which is connected with a dial-up object and with the register. Downloading data from the controller's memory to register 5 is performed completely in parallel or by several groups of signals.

Consider the device of block 3 of FIG. 1 of FIG. 2. Here 1 is a set of external signals sent by an object to control the grating lasers, 2 is a group of signals for selecting a laser power signal, 3 is a key, 4 is a node for issuing laser power signals, 5 is a group of grating lasers, the radiation of which should be directed to one and same RCM module. Node 4 and signal group 2 are common to all blocks 3 and in FIG. 1 are designated 4 and 2, respectively. If the input signal 1 is in the state "1", then the keys of group 3 are included. If the input of the element 4, which forms the laser power signals, receives control signals and the transmitted message - 2, then through the keys the power signals turn on the selected lasers, and the optical signals of the lasers are sent to the RCM module. As will be shown below, the signals emitted by the selected lasers in different situations must have different frequencies. It is preferable to use lasers whose radiation frequency changes when the signal that controls the operation of the laser (for example, control the current supply to the laser) changes. An alternative solution is that the laser has one frequency, which corresponds only to it, of the generated signal. The second option requires more equipment, but lasers with a fixed frequency of generation are now more widespread. Further, the presentation will mainly focus on the availability of tunable lasers.

Thus, the means of FIG. 1 and 2 select the set and frequency of signals sent by the demultiplexer simultaneously for all selected links.

Consider the memory elements added to the prototype RCM module. The design of the new RCM is shown in FIG. 3. Here 1 is a retroreflector, 2, 3, 4 are filters, 5 is a control element with memory, 6-8 are photodetectors, 9 are optical signals entering the RCM and returned to the object. In FIG. Figure 3 shows a retroreflector — a reflector; along with a reflector, a cat-eye retroreflector can be used. New in comparison with the prototype here are the bundles “photodetector of the demultiplexer signal - memory element - light filter”.

Consider the operation of the proposed RCM module. The signals (9) of the lasers coming from outside to the RCM first pass through a sequence of photodetectors 6-8, each of which receives a signal of only one characteristic frequency from the frequencies generated by the lasers. There is the same number of filters, each of which is controlled by a signal coming from the corresponding photodetector filter. Some of the filters are connected directly to the photodetector; for some of the filters, a memory control is placed in the gap of such a connection. To simplify the drawing, two pairs of a photodetector and a filter are shown connected directly and one pair connected through a control element to a memory, although the number of pairs can be arbitrary. When a signal is received from the photodetector, each filter stops passing the frequency that the filter is tuned to, all other frequencies the filters skip. It is also assumed that photodetectors pass through themselves all the frequencies emitted by the lasers. The control with memory 5 allows you to make the filter controlled by it opaque until the memory element is returned to its original state, which makes the filter transparent. It is allowed to use filters and photodetectors with other properties, unless a change in their location, different from the above, does not violate the way this distributed switch is used.

In most distributed switch applications, the laser array area is less than the area occupied by the RCMs. Moreover, it is assumed above that the laser beams exit parallel to each other. The change in direction required for the signal to arrive at the RCM can be achieved in three ways. First, grating lasers can be oriented in the required directions. Secondly, a prism can be installed at the output of each laser, directing the laser beam in the desired direction. Finally, each object can have a system of fixed mirrors, the number of which is equal to the number of RCM modules. These mirrors orient the rays, as shown in FIG. 4. Here 1 is the laser array, 2 are the parallel laser beams, 3 are mirrors directing the laser beams to the RCMs.

In addition to the demultiplexer, the object has a group of photodetectors that receive signals returned by RCMs.

The photodetectors in the object should be located so as to receive all these signals and at the same time not to interfere with the transfer of laser signals to RCM.

Two examples of this arrangement of photodetectors are shown in FIG. 5 and 6. FIG. 5 the beam of one of the lasers 3 of the array of lasers 4 is directed to the RCM-1. Due to diffraction, the beam expands and occupies an area of 2 in RCM, which is larger than the area where the beam exits the laser. The reflected beam has an area of 5 in the object that exceeds the size of the laser array. Within this area, you can place the photodetectors of the object.

In FIG. 6, the beam 4 of one of the lasers of the laser array 5 passes through a partially transparent mirror 2, enters the RCM-1 module, returns it to the mirror 2 with its retroreflector, and is reflected by it in the direction 3 of the location of the object photodetectors. As in FIG. 5, the beam undergoes diffraction not shown for simplicity in FIG. 6.

In FIG. 7 shows the components of a distributed switch used by each dial-up entity. Here 1 is an object, 2 is two retroreflectors, 3 are two groups of photodetectors, 4 are two groups of mirrors directing laser beams to RCM modules, 5 are signals sent between the object and RCM, 6 is an RCM module. The need for two components 2, 3, 4 is caused by the ability of objects to simultaneously send signals to the RCM module for receiving and transmitting messages sent to different RCM modules. This mode is discussed further in the description of the method of using a distributed switch.

In FIG. Figure 8 shows an example of a dial-up system and RCMs. Shown here are m RCM modules and n dial-up objects. Solid lines indicate communications between RCM and message receiver objects, a dashed line indicates communications between a message source and RCM. Connections can be established in dynamics. Here, the source Ο _l sends a message to the receiver O _n , the receivers Ο _l and O _j share a common RCM _k .

It should be noted that in FIG. 7, you can limit yourself to only one demultiplexer in the message source, if you assign specific RCM modules to message receivers, but this will limit the functionality of the switching system and worsen its fault tolerance.

If, in specific applications of the proposed distributed switch, it is possible to exclude the simultaneous transmission of signals to several RCM modules, then the devices in FIG. 1 and 2 are simplified, as shown in FIG. 9 and 10. FIG. 9 lasers are arranged in the form of a lattice. Here, block 1 is the decoder of the address of the rows of the laser gratings, block 5 is the decoder of the address of the columns of the grating of the lasers, block 3 is a group of lasers with a control device, 2 are the inputs of the message signals and service signals, 4 is the block for generating the power signal of the lasers of the grating. Simplification comes down to using short address codes instead of a word with the number of bits equal to the number of RCM modules.

In the modified block 3 shown in FIG. 10, compared with block 3 in FIG. 2 only element 1 logical “AND” was added.

Further simplification is achieved if the possibility of simultaneous transmission of signals of different frequencies to the same RCM module is excluded and a frequency-tunable laser is used. Moreover, in comparison with FIG. 2 in FIG. 10, only one key 3 and one laser 5 remain.

A detailed description of the proposed switching method. Sequentially consider the basic operations performed by the proposed method with the involvement of the proposed system:

- conflict-free message transmission to an individual receiver,

- simultaneous transmission of a message from one source to a group of receivers,

- receiver response to sources,

- simultaneous receipt of a message by the receiver (s) from several sources,

- determination of the possibility of transmitting a message to receivers,

- detection of a conflict of access of sources to the message receiver,

- elimination of the conflict of access of sources to the message receiver.

1. Conflict-free message transmission to an individual receiver. The message source object selects a laser in the array that will send a continuous beam in the direction of the RCM used by the receiver sent by the message source. The message signal transmission frequency f _t is set, and the message is transmitted by turning the beam on or off in accordance with the values of the message bits. In addition to turning on / off a laser operating at a frequency f _t , it is possible to transmit messages by sending laser signals at frequencies f _t1 and f _t2 in accordance with the values of the message bits. The message receiver sends to the RCM module a continuous receive signal having a frequency f _r (or two continuous signals of frequencies f _r1 and f _r2 when the source is working with signals f _t1 and f _t2 ). If necessary, an additional clock signal can also be used. The RCM modulates the signals of the receiver returned to the receiver by the signals of the message source, which ensures the reception of the message from the source.

In addition, the source sends a continuous signal f _{tr to the} above RCM (it may not differ from signal f _r ). The RCM modulates the signal f _{tr with the} signals f _{t of the} message received in the RCM, which allows the source to receive its message sent to the RCM. Any objects that send f _tr signals to this RCM also receive the message transmitted by the source.

2. Simultaneous transmission of a message from one source to a group of receivers. This transmission has two options.

- First option. The source knows the addresses of the receivers. The source object sends signals to blocks 3 (Fig. 2) of its demultiplexer. These blocks will send their signals to the RCM group corresponding to the group of required receivers. Using the power supply unit of the laser power 4 to turn on / off the selected lasers, the source will simultaneously transmit its message to the group of receivers.

- The second option. The addresses of the receivers are unknown. Receivers know the source address. The receiver objects send their signals of frequency f _r to the RCM connected to the source, and at the same time receive a message from the source.

3. The response of the receiver to the sources. The receiver sends a response to the source, modulating its signal f _r . This response will be simultaneously received by all objects sending a continuous signal f _tr to the RCM receiver.

4. Simultaneous receipt of a message by the receiver (s) from several sources. Let there be a group of objects that need to inform other objects about a change in their state, and the first objects do not know the composition of the group of second objects. It may vary depending on the current state of the system as a whole.

In this situation, the first objects set the memory control element 5 in its RCM to the light transmission mode with an appropriate light filter. The initial state of element 5 prohibits the passage of light through the filter. The receiver of such information acts as a source accessing simultaneously all the RCM modules of the objects of the first group. If the receiver detects the return of its signal interrogating the filter controlled by element 5, then it fixes the need to find specific sources that switched element 5. Further, the receiver can use, for example, dichotomous division of addresses of objects of the first group.

5. Determining whether a message can be transmitted to receivers. Two methods are proposed for determining this possibility. The first method does not functionally differ from that used in the prototype, but is implemented taking into account the features of the proposed switch. Sources that need to send a message to the receiver turn on the appropriate laser and send a continuous signal f _r (f _r1 , f _r2 ) to the RCM of this receiver, the same as a continuous signal sent to the RCM receiver. If this signal returned to the source remains continuous, then the receiver does not receive messages from another source and a message can be sent to the receiver. Otherwise, the receiver is already receiving signals and transmission is not possible.

The second method uses the memory controls available in RCM (element 5 in FIG. 3). Let the receiver set this element to a state that allows the retroreflector to return signals, if the receiver allows messages to be received. The message source sends a signal whose return depends on the state of the memory element. If this signal returns to the source, then sending a message is possible. In particular, this method allows you to reserve the right of access to the receiver to a certain group of sources that are allowed to ignore the prohibition of transmitting a message.

6. Detection of conflict of access of sources to the message receiver.

The ability to transmit a message specified in paragraph 5 does not mean its successful execution, since several sources can simultaneously start transmission, and there will be a conflict of access to the receiver. The fastest way to detect conflict is as follows. The message transmitting source simultaneously sends a continuous signal to the receiver RCM, in particular the signal f _r . This signal is returned from the RCM to the source by modulated source message signals. If there are overlays of other signals, this means that there is an access conflict. In addition, a receiver detects a message corruption (for example, by checking the checksum of the message), which will send an error message to the sources.

7. Elimination of the conflict of access of sources to the message receiver. We assume that the location of the switched objects and RCM is fixed. This allows you to pre-calculate all the required distances between the above devices and make a list of transmission times of the signal T _ij between them. Such calculations can be carried out in dynamics as needed. Further actions do not differ from the way to resolve conflicts in the prototype.

Let the sources know l - the number of sources that are allowed to access this receiver, and these sources are ordered. A conflict message triggers the synchronization of the following source actions.

посылает сообщение в RCM. Здесь T_max≥maxT_ij, ij=1, …, l. Все такие сообщения поступят в RCM одновременно, с задержкой T_max. Таким образом, все сообщения группы источников в RCM накладываются одно на другое и представят собой единое сообщение. В него каждый конфликтующий источник вносит единицу в разряд сообщения, соответствующий порядковому номеру (приоритету) источника. RCM возвратит сообщение всем его источникам, что позволит последним определить момент времени начала новой передачи своего сообщения. Далее каждый конфликтующий источник S_i передает свое сообщение с задержкой T_max-T_ij+Q, где Q - суммарная длительность сообщений, переданных источниками с более высоким приоритетом (считается, что Q известно источнику). Конфликт устранен.Conflicting sources send a coordinating binary message containing l bits to RCM. This message is sent as follows. Having detected a transmission conflict with the receiver number j, the conflicting source S _i with a delay

sends a message to RCM. Here T _max ≥maxT _ij , ij = 1, ..., l. All such messages will arrive at RCM simultaneously, with a delay T _max . Thus, all messages from a group of sources in RCM are superimposed on one another and will be a single message. In it, each conflicting source contributes a unit to the message category corresponding to the serial number (priority) of the source. RCM will return the message to all its sources, which will allow the latter to determine the point in time for the start of a new transmission of its message. Next, each conflicting source S _i transmits its message with a delay T _max -T _ij + Q, where Q is the total duration of messages transmitted by sources with a higher priority (it is believed that Q is known to the source). Conflict resolved.

Instead of the calculation procedure T _ij, you can use the prototype method, which measures the dynamics of the propagation times of signals between objects and RCM using additional equipment.

Claims (2)

1. A method of laser wireless retroreflective distributed optical switching, in which the source participating in the switching to select the receiving objects, the receivers selects in the demultiplexer and turns on lasers to send signals simultaneously to the group of retroreflector modules assigned to the receivers and through them receivers, modulating the source signals receiver signals sent to the module by the receiver and returned to it by the module, and the receiver memorizes the corresponding retr reflex module information about the state of the receiver, and the source reads the state of this memory to select its actions with the receiver. 2. The system of laser wireless retroreflector distributed optical switching, characterized in that it contains demultiplexers participating in the switching object with a group of lasers selected and turned on by this object, and containing retroreflector modules outside the objects participating in the switching, and only one of the retroreflector constantly corresponds to each demultiplexer laser modules receiving signals transmitted in free space from this laser and returning them in the direction of the source signal moreover, the laser signals arriving at the module differ in frequency, each retroreflector module corresponding to one or several objects participating in the switching and contains binary memory elements controlled by this object and prohibiting or allowing the retroreflector module to return the signal received from the demultiplexer if the memory element set accordingly to the prohibiting or allowing signal return state.

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